1. Field of the Invention
The present invention relates to an image-capturing apparatus having an image-capturing optical system.
2. Description of the Related Art
A single-lens reflex camera (image-capturing apparatus) is configured to have a mirror unit including a main mirror and a sub-mirror that can be driven so that when the mirror unit is tilted down, object light that has been transmitted through an image-capturing lens is guided to an auto-focus (AF) module (phase-difference AF module) of a phase-difference detection method and an optical finder and also, when the mirror unit is tilted up, object light is guided to an image-capturing plane.
In continuous image capturing in such a camera, phase-difference AF using an AF module can be performed by down-driving and up-driving the mirror unit during intervals between actual exposures to an image-capturing plane and guiding object light to the AF module (see Japanese Unexamined Patent Application Publication No. 8-43914).